Brush material for intelligent household electrical appliances and preparation method thereof

Abstract

The invention discloses a motor brush material for intelligent household appliances and a preparation method thereof, and the preparation method comprises the following steps: mixing matrix graphite powder with a composite binder to prepare mixed particles, and crushing, screening and mixing to prepare brush matrix powder; the method comprises the following steps: preparing powder into a brush green body through compression molding, roasting the green body under the protection of a combined atmosphere of nitrogen and hydrogen to prepare a brush cooked body with a porous structure, and carrying out negative pressure dipping treatment on the brush cooked body to prepare the brush material. The prepared electric brush material has the advantages of being long in service life, good in reversing performance, low in spark grade, low in noise, capable of reducing heating during motor operation, capable of improving energy efficiency and the like.

Description

Technical Field

[0001] The invention relates to a method for preparing a motor brush material for intelligent household appliances, in particular to a method for preparing a long-life porous brush material, belonging to the field of materials. Technical Background

[0002] The brush is one of the main components for conducting current between the rotating part and the stationary part of the DC motor. It is used as the commutation component of the motor and also as a sliding contact for introducing and extracting current. The brush has good electrical conductivity, thermal conductivity and lubrication properties, and has a certain mechanical strength. Almost all DC motors and commutation motors use brushes, so they are an important part of the motor.

[0003] With the development of science and technology, the types of motors and the working conditions of their use are becoming more and more diverse. Therefore, different types of brushes are needed to meet the various requirements of motors. Therefore, the types of brushes are also increasing with the development of the motor industry.

[0004] At present, there are four main classification methods for brushes: (1) According to the hardness of the material, they can be divided into soft brushes, medium-hard brushes and hard brushes; (2) According to the use of the brushes, they can be divided into brushes for steam turbine generators, brushes for steel rolling motors, brushes for traction motors, brushes for automobiles and tractors, brushes for household appliance motors, brushes for power tools, brushes for automobile motors, brushes for aircraft motors, etc.; (3) According to the color of the brushes, they can be divided into black brushes (made of pure carbon graphite materials) and colored brushes (made of metal materials such as copper and graphite); (4) According to the different materials of the brushes, they can be divided into graphite brushes, electroplated graphite brushes, metal graphite brushes, and pure metal brushes.

[0005] Household electrical appliances are generally DC motors. Due to the needs of their application environment, brushes are required to have the advantages of good spark suppression and low brush noise. Specifically, the requirements are as follows: (1) Long service life and no wear on the commutator, no scratches, unevenness, burning, wire drawing, etc. on the commutator; (2) Good commutation performance and low energy loss; (3) When the brush is running, it does not overheat, has low noise, is not damaged, and does not burn. Summary of the invention

[0006] The purpose of the present invention is to solve the current technical problems of large sparks when starting household electrical appliances, burning commutator, abnormal noise, excessive temperature rise, etc., and to provide a motor brush material for intelligent household appliances and a preparation method thereof. The brush prepared by the method of the present invention not only has a low friction coefficient, good wear resistance, good commutation performance, and low spark level, but more importantly, the brush has a porous structure, low noise, and good thermal conductivity.

[0007] To achieve the purpose of the present invention, the present invention provides a method for preparing a brush material for a motor of a smart home appliance, comprising the following steps:

[0008] A) First, the base graphite powder is stirred and heated in a kneading pot, so that the temperature of the base graphite powder rises to 110-130°C (preferably 120°C); then, under a closed condition, a composite binder is added, and stirring and heating are continued until the temperature of the mixture reaches 170-180°C (preferably 180°C); then, under the condition of maintaining the temperature of the mixture at 170-180°C (preferably 180°C), the stirring treatment is continued for at least 1 hour, and then the heating is stopped, and the closed state is ended, and stirring is continued for at least 0.25 hours; then, it is naturally cooled to room temperature to obtain a brush base mixture;

[0009] B) crushing and sieving the brush matrix mixture to obtain brush matrix powder;

[0010] C) stirring and mixing the brush base powder and the metal base composite agent to obtain a brush raw material mixture powder;

[0011] D) forming a brush green body from the brush raw material mixture powder by compression molding;

[0012] E) calcining the brush blank to obtain a cooked brush blank;

[0013] F) Under negative pressure conditions, the brush blank is impregnated to obtain the target brush material.

[0014] Wherein, the weight ratio of the matrix graphite powder and the composite binder in step A) is 100:

[0015] (10-30), preferably 100:28.

[0016] In particular, the matrix graphite powder in step A) includes natural graphite and artificial graphite powder.

[0017] Particularly, the weight ratio of the natural graphite to the artificial toner is (3-4):(1-2), preferably 4:(1-2), and more preferably 4:2.

[0018] In particular, the composite binder in step A) includes high-temperature coal tar, insoluble sulfur powder, and liquid paraffin.

[0019] In particular, the weight ratio of the high-temperature coal tar, sulfur powder and liquid paraffin is 100:(15-25):(15-25), preferably 100:20:20.

[0020] Adding liquid paraffin to the composite binder changes the viscosity of high-temperature coal tar at high temperatures, allowing the base graphite powder and the binder to be mixed more fully; insoluble sulfur penetrating into the asphalt can modify the binder and improve the mechanical properties of the mixture.

[0021] In particular, after the composite adhesive is added, the material temperature is raised to 170-180° C. at a heating rate of 50-65° C. / h, preferably 60° C. / h.

[0022] Particularly, the mixed material is stirred at a temperature of 170-180° C. for 1-1.5 h, preferably 1 h.

[0023] The mixing time under closed conditions in step A) is 2-2.5 hours (including two stages of closed mixing a, heating to 180°C for 1 hour and keeping at 180°C for 1 hour to 1.5 hours after adding the binder), preferably 2 hours. The purpose of closed mixing is to prevent volatile components such as sulfur in the binder from volatilizing and overflowing prematurely to affect the mixing effect.

[0024] During the mixing process, the material temperature was monitored every 30 minutes. When the material temperature reached 180°C, the oil temperature was then lowered to 180°C to stabilize the material temperature at 180°C.

[0025] Wherein, in the process of raising the temperature of the mixed material to 180°C, the heating rate is 50-65°C / h, preferably 60°C / h.

[0026] In particular, the time for the mixed material temperature to stabilize at 180°C is 60 -90 min, preferably 60 min.

[0027] During the process, the maximum temperature of the mixture is 180°C. Stop heating, open the kneading pot cover and continue mixing for 30 minutes (usually 0.25-1h) before discharging the material and cooling it naturally to obtain the brush raw material mixed particles.

[0028] Wherein, the particle size of the brush base powder in step B) is ≤80 mesh.

[0029] Wherein, the metal matrix composite agent in step C) includes copper powder and molybdenum disulfide powder.

[0030] In particular, the weight ratio of the copper powder to molybdenum disulfide is (30-40):1), preferably 34:1.

[0031] Particularly, the weight ratio of the brush matrix powder to the metal matrix composite agent is (20-40):(60-80), preferably 30:(60-80), more preferably 30:(66-74), and even more preferably 30:70.

[0032] In particular, the weight ratio of the electrolytic copper powder, molybdenum disulfide and brush matrix powder is (216-238):(6.4-7.0):100, preferably 226.7:6.67:100.

[0033] In particular, the composite binder in step A) is a mixture of high-temperature coal tar, liquid paraffin and sulfur powder.

[0034] In particular, the mixing temperature of the matrix graphite and the binder in step A) is 120° C., and the temperature rises to 180° C. at the highest during the mixing process.

[0035] In particular, in step A), the matrix graphite and the composite binder are mixed in a closed manner for 2 hours under closed conditions.

[0036] In particular, the volume density of the brush green body molded in step D) is 4.0 to 4.7 g / cm 3 , preferably 4.5 g / cm 3 .

[0037] In particular, in step D), the pressure during the compression molding process is controlled to be 10-20 MPa; the compression molding time is 0.5-1.5S, preferably 1S.

[0038] In particular, the maximum calcination temperature in step E) is 600°C.

[0039] In particular, the calcination process is divided into 7 stages, the highest calcination temperature is 590-610° C. (preferably 600° C.), and the calcination temperature increases successively from the first stage to the seventh stage.

[0040] In particular, the temperatures of the 7 roasting stages are:

[0041] The first stage calcination temperature is 150-250°C, preferably 200°C;

[0042] The second stage calcination temperature is 250-300°C, preferably 280°C;

[0043] The third stage calcination temperature is 350-400°C, preferably 380°C;

[0044] The fourth stage calcination temperature is 450-520°C, preferably 500°C;

[0045] The fifth stage calcination temperature is 530-560°C, preferably 550°C;

[0046] The sixth stage calcination temperature is 590-610°C, preferably 600°C;

[0047] The seventh stage calcination temperature is 590-610°C, preferably 600°C;

[0048] In particular, the time of the seven calcination stages in the calcination process is 1.5-1.83h, 1.5-1.83h, 1.5-1.83h, 1.5-1.83h, 1.5-1.83h, 1.5-1.83h, 1.5-1.83h, and 1.5-1.83h, respectively, and preferably 1.7h, 1.7h, 1.7h, 1.7h, 1.7h, 1.7h, 1.7h, and 1.7h.

[0049] During the calcination process, the liquid paraffin component contained in the material volatilizes at high temperature, the porosity is improved and becomes more uniform, and has a positive effect on the running noise, heat dissipation and sparks of the brush, which is of great significance to the present invention.

[0050] Wherein, in step F), the brush blank is impregnated with a composite impregnation oil under negative pressure.

[0051] Particularly, the composite impregnation oil solution comprises impregnation oil and acetone.

[0052] Particularly, the weight ratio of the impregnation oil to acetone is (0.05-1.5):1, preferably 1:1.

[0053] Particularly, the impregnating oil is selected from one or more of silicone oil and multi-component synthetic oil, preferably silicone oil.

[0054] Particularly, the negative pressure condition is a relative pressure of -60 to -40 KPa, preferably -50 KPa.

[0055] In particular, the method further comprises centrifuging the impregnated blank at 110-130° C. (preferably 120° C.), wherein the centrifugal speed is 600-1000 rpm (preferably 800 rpm); and the centrifugal time is 25-50 min, preferably 30 min.

[0056] In particular, the blank is further dried after the centrifugal treatment, that is, the blank after the centrifugal treatment is placed in an oven at a temperature of 110-130° C. (preferably 120° C.) and dried for at least 6 hours, preferably 6-12 hours.

[0057] In step A), when the base graphite powder is stirred and heated in a kneading pot to 110-130° C. (preferably 120° C.), a composite binder is added to perform a first closed stirring process, and the mixing temperature gradually increases during the first closed stirring process until it reaches 170-180° C. (preferably 180° C.), and then a second closed stirring process is performed under the condition of maintaining the temperature at 170-180° C. (preferably 180° C.); then the heating is stopped and the kneading pot cover is opened to continue the third stirring and mixing process; after the third mixing process for 0.25-1h (preferably 0.5h), the material is discharged and naturally cooled to obtain a brush base mixture;

[0058] In particular, the first closed stirring treatment time is 0.5-1.5h, preferably 1h; the temperature during the first closed stirring treatment is lower than 180°C; the second closed stirring treatment is 170-180°C, preferably 180°C; the second closed stirring treatment time is 1-1.5h, preferably 1h; the third stirring and mixing treatment time is 0.25-1h, preferably 0.5h.

[0059] In particular, the heating rate during the second closed stirring treatment is 50-65°C / h, preferably 60°C / h.

[0060] The brush base powder, electrolytic copper powder and molybdenum disulfide powder are added into a double-shaft mixer for a fourth mixing treatment, wherein the fourth mixing treatment time is 0.5-1.5 h (preferably 1 h), to obtain a brush raw material mixture powder.

[0061] The brush raw material mixture powder is added into a pressing mold by a hydraulic press, and the mixture is pressed to obtain a brush blank.

[0062] During the pressing process, the volume density of the brush blank is controlled to be 4.0-4.7 g / cm 3

[0063] The brush blank is subjected to a sintering treatment to obtain a brush blank material.

[0064] In particular, the calcination maximum temperature is 600°C.

[0065] In particular, the calcination process is divided into 7 stages, the highest calcination temperature is 590-610° C. (preferably 600° C.), and the calcination temperature increases successively from the first stage to the seventh stage.

[0066] In particular, the temperatures of the 7 roasting stages are:

[0067] The first stage calcination temperature is 150-250°C, preferably 200°C;

[0068] The second stage calcination temperature is 250-300°C, preferably 280°C;

[0069] The third stage calcination temperature is 350-400°C, preferably 380°C;

[0070] The fourth stage calcination temperature is 450-520°C, preferably 500°C;

[0071] The fifth stage calcination temperature is 530-560°C, preferably 550°C;

[0072] The sixth stage calcination temperature is 590-610°C, preferably 600°C;

[0073] The seventh stage calcination temperature is 590-610°C, preferably 600°C;

[0074] Particularly, the brush blank is placed in a baking box and put into a mesh belt furnace for the baking treatment.

[0075] In particular, the mesh belt speed of the roasting treatment is 50-70 cm / h, preferably 60 cm / h.

[0076] In particular, the time of the seven calcination stages in the calcination process is 1.5-1.83h, 1.5-1.83h, 1.5-1.83h, 1.5-1.83h, 1.5-1.83h, 1.5-1.83h, 1.5-1.83h, and 1.5-1.83h, respectively, and preferably 1.7h, 1.7h, 1.7h, 1.7h, 1.7h, 1.7h, 1.7h, and 1.7h.

[0077] During the roasting process, the lengths of the seven temperature zones are 90-110cm, 90-110cm, 90-110cm, 90-110cm, 90-110cm, 90-110cm, 90-110cm, and 90-110cm, respectively, and preferably 100cm, 100cm, 100cm, 100cm, 100cm, 100cm, 100cm, and 100cm.

[0078] The brush blank impregnation process includes heating the blank in the impregnation machine, evacuating the negative pressure, adding the impregnation liquid, impregnating for 5 to 10 minutes, centrifuging, taking out and drying in a 120°C drying oven for 6 hours.

[0079] In particular, the porous structure of the brush blank allows the impregnation oil to be more evenly impregnated into the interior of the brush. This process can significantly reduce sparks during brush operation.

[0080] Compared with the prior art, the brush for the motor of the smart household appliance of the present invention has the following advantages:

[0081] 1. The raw material of the brush of the present invention innovatively uses liquid paraffin modified binder, and the prepared brush material has a long service life and high stability, which can meet the requirements of long-term use of smart home appliance motors.

[0082] 2. The brush material of the present invention has uniform internal voids, which can absorb part of the brush vibration generated by the operation of the motor, reduce the operating noise, and make the motor quieter and more environmentally friendly during use.

[0083] 3. The internal pores of the brush material of the present invention can be evenly impregnated with oil, so that the brush is in full contact with the motor commutator, reducing the sparks during motor operation, improving efficiency, and reducing the energy consumption of the motor; the oil can enhance lubricity, reduce the operating temperature of the commutator, inhibit sparks, reduce noise, and extend the service life of the brush.

[0084] 4. In the material preparation process of the present invention, the impregnation is controllable, and the impregnation rate can be increased by extending the impregnation time, and the oil impregnation rate can also be reduced by extending the centrifugation time. BRIEF DESCRIPTION OF THE DRAWINGS

[0085] Figure 1 The present invention is a flow chart for preparing the motor brush material for smart home appliances. DETAILED DESCRIPTION

[0086] The present invention will be further described below in conjunction with specific embodiments, and the advantages and features of the present invention will become clearer as the description proceeds. However, these embodiments are exemplary only and do not constitute any limitation to the scope of the present invention. It should be understood by those skilled in the art that the details and forms of the technical solution of the present invention may be modified or replaced without departing from the spirit and scope of the present invention, but these modifications and replacements all fall within the scope of protection of the present invention.

[0087] Example 1

[0088] 1. Prepare ingredients:

[0089] 1A) Prepare the matrix graphite powder according to the following weight ratio (kg):

[0090] Natural graphite 80

[0091] Artificial graphite 20

[0092] 1B) Prepare the composite binder according to the following weight ratio (kg):

[0093] High temperature coal tar 20

[0094] Insoluble Sulfur 4

[0095] Liquid paraffin 4

[0096] 1C) Prepare the metal matrix composite according to the following weight ratio (kg):

[0097] Electrolytic copper 226.67

[0098] Molybdenum disulfide 6.67

[0099] Among them: the particle size of electrolytic copper powder and molybdenum disulfide is ≤80 mesh. Copper powder can enhance the conductivity and reduce the material resistance; molybdenum disulfide increases the lubricity of the material, reduces the sliding friction resistance, and reduces the heat generation during operation.

[0100] The metal matrix composite in the present invention needs to ensure uniform mixing of the composite when taking the metal matrix composite, which requires additional mixing times; however, too many mixing times will lead to increased errors in various proportions; therefore, the present invention first confirms the amount of matrix powder, then calculates the metal matrix composite machine ratio, and directly mixes them synchronously.

[0101] 1D) Prepare the composite impregnation oil according to the following weight ratio (×100kg):

[0102] Impregnation oil (silicone oil) 1

[0103] Acetone 1

[0104] The impregnation oil may be a multi-component synthetic oil in addition to silicone oil.

[0105] In the specific implementation manner of the present invention, the mass ratio of natural graphite to artificial graphite is 4:1 as an example, and other ratios such as (3-4): (1-2) are all applicable to the present invention; the mass ratio of high-temperature coal tar, sulfur, and liquid paraffin in the composite binder is 100:20:20 (i.e., 20:4:4) as an example, and other ratios of 100: (15-25): (15-25) are all applicable to the present invention; the impregnating oil in the composite impregnating oil liquid is silicone oil as an example, and other multi-component artificial synthetic oils are all applicable to the present invention; the mass ratio of silicone oil to acetone is 1:1 as an example, and other ratios of 0.05-1.5): 1 are all applicable to the present invention.

[0106] 2. Preparation of brush base powder

[0107] 2A) crushing the high-temperature coal tar into particles smaller than 25 mesh, and then stirring and mixing the high-temperature coal tar particles, insoluble sulfur, and liquid paraffin to obtain a composite binder;

[0108] 2B) natural graphite and artificial graphite are placed in a kneading pot, the oil temperature of the kneading pot is set to 200°C, the rotating device and heating device of the kneading pot are turned on, and the material temperature of the mixed graphite powder is measured during the coagulation process until the temperature of the graphite powder reaches 120°C (usually 110-130°C), and the natural graphite and artificial graphite are kneaded for 1 hour (usually 0.5-1.5 hours);

[0109] Setting the kneading pot oil temperature (200°C) higher than the maximum material temperature can reduce the heating time. If the mixing time is too long, the kneading effect will be negative. When the material temperature reaches (180°C), adjust the kneading pot oil temperature to 180°C to stabilize the maximum material temperature at 180°C.

[0110] The softening point of asphalt in the binder is generally below 120°C. Asphalt needs to be softened and mixed during the hot mixing process to ensure the uniformity of the mixing. The material heating rate is controlled by increasing / decreasing the oil temperature. The heating rate is generally controlled to reach a maximum of 180°C (60°C / h) about 1 hour after the addition of the binder. Asphalt in the binder is prone to aging at temperatures above 180°C, which reduces the overall performance of the material.

[0111] 2C) Add the composite binder to the kneading pot, cover the sealing cover, and perform the first closed stirring process to mix evenly. During the first closed mixing, measure the temperature of the mixed material. When it reaches 180°C (usually 170-180°C), adjust the oil temperature of the kneading pot to 180°C (usually 170-180°C), and continue the second closed stirring process, wherein the first closed stirring is 1h (usually 0.5-1.5h); the heating rate during the process of heating to 180°C (usually 170-180°C) is 60°C / h (usually 50-65°C / h); after the second closed stirring process for 1h (usually 1-1.5h), open the sealing cover, stop heating, and continue the third stirring and mixing process;

[0112] 2D) After the third stirring and mixing treatment for 0.5 h (usually 0.25-1 h), the mixed material is taken out, placed at room temperature, spread evenly, and allowed to stand at room temperature to obtain a brush matrix mixture;

[0113] 2E) The brush matrix mixture is placed in an automatic pulverizer for crushing at a crushing speed of 1000 rpm, and the crushed material is passed through an 80-mesh sieve to obtain a brush matrix powder, the particle size of the brush matrix powder being ≤80 mesh.

[0114] 3. Preparation of brush raw material mixture powder

[0115] Pour the brush base powder and the metal base composite (electrolytic copper powder, molybdenum disulfide powder) into a double-shaft cold mixer, and perform a fourth mixing treatment for 1 hour (usually 0.5-1.5 hours) to obtain a raw material mixture powder, wherein the weight ratio of the brush base powder to the metal base composite is 30:70 (usually (20-40): (60-80)), and the weight ratio of the electrolytic copper powder to molybdenum disulfide in the metal base composite is 33.98:1 (usually (30-40): 1); the weight ratio of the brush base powder, electrolytic copper powder, and molybdenum disulfide is 30:68:2 (the weight ratio of the base powder, electrolytic copper powder, and molybdenum disulfide is usually 100: (216-238): (6.4-7.0));

[0116] The fourth mixing was performed at room temperature with a rotation speed of 23 r / min.

[0117] 4. Suppression treatment

[0118] The obtained brush raw material mixture powder was placed in a pressing mold and pressed using a hydraulic press to obtain a powder with a volume density of 4.5 g / cm 3 (Usually 4.0~4.7g / cm 3 ) of the brush blank; the pressure during the pressing process is 18MPa (usually 10-20MPa), and the pressure is maintained for 1S (usually 0.5-1.5S).

[0119] The present invention controls the bulk density of the blank during the pressing process, so as to control static properties such as density, resistivity, hardness, and bending resistance of the final material.

[0120] 5. Calcination

[0121] The brush blank is placed in a baking box, put into a mesh belt furnace, and baked under the protection of nitrogen / hydrogen combination gas to obtain the brush blank material, wherein: the hydrogen flow rate inside the mesh belt furnace is 2.5m 3 / h(usually 2-3m 3 / h), nitrogen flow rate 13m 3 / h (usually 12-14m 3 / h), the volume ratio of nitrogen / hydrogen is 5.2:1 (usually (4-7):1); the net belt speed is 60cm / h (usually 50-70cm / h), 7 temperature zones: 200℃-280℃-380℃-500℃-550℃-600℃-600℃; the lengths of the 7 temperature zones are 100, 100, 100, 100, 100, 100, 100cm respectively;

[0122] The temperatures of the 7 temperature zones are usually: 150-250℃, 250-300℃, 350-400℃, 450-520℃, 530-560℃, 590-610℃, 590-610℃; the lengths of the 7 temperature zones are 100, 100, 100, 100, 100, 100cm respectively.

[0123] During the roasting process, nitrogen / hydrogen acts to isolate oxygen and prevent the material from high-temperature oxidation.

[0124] 6. Impregnation treatment

[0125] Mix the silicone oil and acetone evenly to prepare an enriched impregnation oil solution for later use;

[0126] The brush blank material is placed in the impregnation machine, and vacuum is drawn to make the relative pressure in the impregnation machine reach -50KPa (usually -60~-40KPa), and then the composite impregnation oil is added. After the composite impregnation oil submerges the brush blank material, it is left to stand for 10 minutes (usually 5-10 minutes), and then the composite impregnation oil is released;

[0127] The impregnated brush material is heated to 120°C (usually 110-130°C) in an impregnation machine, and the speed is adjusted to 800r / min (usually 600-1000r / min) for centrifugal drying for 30 minutes. The material is taken out and dried in a drying oven at 120°C for 6 hours, and naturally cooled to obtain the brush material of the present invention.

[0128] The volume density of the brush material was measured according to the method of JB / T8133.14-1999 (physical and chemical properties test method for electric carbon products, volume density); the resistivity of the brush material was measured according to the method of JB / T8133.2-1999 (physical and chemical properties test method for electric carbon products, resistivity); the Shore hardness of the brush material was tested using the HS-19CTV hardness tester; the flexural strength of the brush material was measured using the method of JB / T8133.7-1999 (physical and chemical properties test method for electric carbon products, flexural strength); the test results are shown in Table 1;

[0129] The wear rate of the motor brushes was tested using the FNC-5 load endurance test controller. The test results are shown in Table 2.

[0130] The efficiency of the motor brushes was tested with reference to the national standard "Test method for determining losses and efficiency of rotating electrical machines (except traction motors) (GB / T755.2-2003)". The test results are shown in Table 3.

[0131] Table 1 Test results of physical and mechanical properties of brush materials

[0132] <![CDATA[Bulk density (g / cm 3 )]]> Shore hardness (HSD) Resistivity (μΩ·m) Flexural strength(MPa) Detection Group 1 4.45 21 0.25 53 Detection Group 2 4.43 22 0.25 52 Detection Group 3 4.44 23 0.26 52 Detection Group 4 4.45 21 0.26 51 Mean 4.44 22 0.26 52

[0133] Table 2 Brush wear rate test results

[0134]

[0135] Table 3 Brush efficiency test results

[0136]

[0137] Example 2

[0138] 1. Prepare ingredients:

[0139] 1A) Prepare graphite matrix powder according to the following weight ratio (kg):

[0140] Natural graphite 80

[0141] Artificial graphite 20

[0142] 1B) Prepare the composite binder according to the following weight ratio (kg):

[0143] High temperature coal tar 20

[0144] Insoluble Sulfur 4

[0145] Liquid paraffin 4

[0146] 1C) Prepare the metal matrix composite according to the following weight ratio (kg):

[0147] Electrolytic copper 238

[0148] Molybdenum disulfide 7.0

[0149] 1D) Prepare the composite impregnation oil according to the following weight ratio (×100kg):

[0150] Impregnation oil (silicone oil) 1

[0151] Acetone 1

[0152] 2. Preparation of brush base powder

[0153] Same as step 2 of Example 1.

[0154] 3. Preparation of brush raw material mixture powder

[0155] Except that the weight ratio of the brush base powder to the metal base composite is 30:73.5 (usually (20-40):(60-80)), the weight ratio of the electrolytic copper powder to molybdenum disulfide in the metal base composite is 34:1 (usually (30-40):1); the weight ratio of the brush base powder, electrolytic copper powder and molybdenum disulfide is 30:71.4:2.1 (100:238:7) (the weight ratio of the base powder, electrolytic copper powder and molybdenum disulfide is usually 100:(216-238):(6.4-7.0)), the rest is the same as step 3 of Example 1.

[0156] 4. Suppression treatment

[0157] In addition to the pressure of 13Mpa (usually 10-20Mpa) during the pressing process, the pressure holding time is 1S, and the volume density of the brush blank is 4.25g / cm 3 (Usually 4.0~4.7g / cm 3 ), the rest is the same as step 4 of Example 1.

[0158] 5. Calcination

[0159] Step 5 of Example 1 is the same.

[0160] The test results of the physical and mechanical properties of the brush material are shown in Table 4; the test results of the wear rate and efficiency of the brushes made of the brush material are shown in Table 5.

[0161] Example 3

[0162] 1. Prepare ingredients:

[0163] 1A) Prepare graphite matrix powder according to the following weight ratio (kg):

[0164] Natural graphite 80

[0165] Artificial graphite 20

[0166] 1B) Prepare the composite binder according to the following weight ratio (kg):

[0167] High temperature coal tar 20

[0168] Insoluble Sulfur 4

[0169] Liquid paraffin 4

[0170] 1C) Prepare the metal matrix composite according to the following weight ratio (kg):

[0171] Electrolytic copper 216

[0172] Molybdenum disulfide 6.4

[0173] 1D) Prepare the composite impregnation oil according to the following weight ratio (×100kg):

[0174] Impregnation oil (silicone oil) 1

[0175] Acetone 1

[0176] 2. Preparation of brush base powder

[0177] The same as step 2 of Example 1.

[0178] 3. Preparation of brush raw material mixture powder

[0179] Except that the weight ratio of the brush base powder to the metal base composite is 30:66.7 (usually (20-40): (60-80)), the weight ratio of the electrolytic copper powder to molybdenum disulfide in the metal base composite is 33.75:1 (usually (30-40): 1); the weight ratio of the brush base powder, electrolytic copper powder and molybdenum disulfide is 30:64.8:1.92 (the weight ratio of the base powder, electrolytic copper powder and molybdenum disulfide is usually (100): (216-238): (6.4-7.0)), the rest is the same as step 3 of Example 1.

[0180] 4. Suppression treatment

[0181] In addition to the pressure of 19MPa (usually 10-20MPa) during the pressing process, the pressure holding time is 1S, and the volume density of the brush blank is 4.5g / cm 3 (Usually 4.0~4.7g / cm 3 ), the rest is the same as step 4 of Example 1.

[0182] 5. Calcination

[0183] Same as step 5 of Example 1.

[0184] The test results of the physical and mechanical properties of the brush material are shown in Table 4; the test results of the wear rate and efficiency of the brushes made of the brush material are shown in Table 5.

[0185] Table 4 Test results of mechanical properties of brush materials

[0186] <![CDATA[Bulk density (g / cm 3 )]]> Shore hardness (HSD) Resistivity (μΩ·m) Flexural strength(MPa) Example 2 4.20 22 0.24 50 Example 3 4.41 21 0.28 51

[0187] Table 5 Brush wear rate and efficiency test results

[0188] Wear rate (mm / 1000H) efficiency(%) Example 2 1.76 82.1 Example 3 1.75 81.9

[0189] The terms used in the present invention are illustrative and exemplary, rather than restrictive. Since the present invention can be implemented in various forms without departing from the spirit or essence of the technical solution, it should be understood that the above embodiments are not limited to any of the aforementioned details, but should be widely interpreted within the spirit and scope defined by the attached claims, so all changes and modifications falling within the scope of the claims or their equivalents are covered by the attached claims.

Claims

1. A method for preparing a motor brush material for smart home appliances, characterized in that: The steps include: A) First, the base graphite powder is stirred and heated in a kneading pot, so that the temperature of the base graphite powder rises to 110-130°C; then, under a closed condition, a composite binder is added, and stirring and heating are continued until the temperature of the mixture reaches 170-180°C; then, under the condition of maintaining the temperature of the mixture at 170-180°C, the stirring treatment is continued for at least 1 hour, and then the heating is stopped, and the closed state is ended, and stirring is continued for at least 0.25 hours; then, it is naturally cooled to room temperature to obtain a brush base mixture; B) crushing and sieving the brush matrix mixture to obtain brush matrix powder; C) stirring and mixing the brush base powder and the metal base composite agent to obtain a brush raw material mixture powder; D) forming a brush green body from the brush raw material mixture powder by compression molding; E) calcining the brush blank to obtain a cooked brush blank; F) Under negative pressure conditions, the brush blank is impregnated to obtain the target brush material.

2. The preparation method according to claim 1, characterized in that: The weight ratio of the matrix graphite powder and the composite binder in step A) is 100:(10-30).

3. The preparation method according to claim 1 or 2, characterized in that: The matrix graphite powder in step A) includes natural graphite and artificial graphite powder.

4. The preparation method according to claim 1 or 2, characterized in that: The composite binder in step A) includes high-temperature coal tar, insoluble sulfur powder and liquid paraffin.

5. The preparation method according to claim 1 or 2, characterized in that: The metal matrix composite agent in step C) includes copper powder and molybdenum disulfide powder.

6. The preparation method according to claim 1, characterized in that: In step A), the mixing temperature of the matrix graphite and the binder is 120° C., and the temperature rises to 180° C. at the highest during the mixing process.

7. The preparation method according to claim 1 or 2, characterized in that: The volume density of the brush green body molded in step D) is 4.0-4.7 g / cm 3 , preferably 4.5 g / cm 3 .

8. The preparation method according to claim 1 or 2, characterized in that: The maximum temperature of the calcination treatment in step E) is 600°C.

9. The preparation method according to claim 1, characterized in that: The negative pressure condition in step F) is a relative pressure of -60 to -40 KPa, preferably -50 KPa.

10. A motor brush material for smart home appliances, characterized in that: Prepared according to the method as described in any one of claims 1 to 9.

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